Humans are a species with a high capacity to adapt to new environments and situations, including extreme temperatures. The problem arises when we want to know what the limits of our tolerance and adaptability are, especially when a significant portion of humanity lives close to those limits.

Heat waves in the Iberian Peninsula.
Continental Spain suffered a heat wave accompanied by a significant increase in mortality rates much higher than expected. According to data provided by the Carlos III Institute of Health, so far in 2022, the extreme death toll from temperatures has been almost 4,800 people. Of these, 3,767 correspond to the period between May 1 and today. The situation is similar in Portugal and elsewhere in the world.

Effects of temperature on health.
That this heat poses health risks is nothing new. Heatstroke can kill us and is especially dangerous for the very young and very old. Dehydration can also damage the kidneys and heart. Fatigue is one of the (not always) less serious effects of heat, but it can also be a burden in our daily lives.

Heat can also affect us on a psychological level. In this sense, it can increase our aggression and at the same time reduce our ability to concentrate. In addition to the fatigue caused by lack of sleep, our productivity also decreases.

It’s a difficult question to answer.
As always in science, this is not an easy question to answer. There is no maximum temperature our body shuts down or a specific time it can withstand. Our capacity varies greatly from person to person and affects not only temperature and time, but also, for example, humidity.

Humidity is closely related to our ability to resist heat, because one of our main internal mechanisms that regulates our temperature depends precisely on water: sweat.

Approach the border.
A measure based on scientific studies that has been determined in recent years to be the limit of human endurance, the point at which the body cannot regulate its temperature, is equivalent to a temperature of 35 degrees Celsius at 100% humidity. This corresponds to a heat index of around 70 relative to the equivalents used by the State Meteorological Agency AEMET. The “real world” limit is likely to be well below that.

The extreme danger for AEMET begins at a heat index of 54. In the case of 50% humidity, reaching 40 degrees may be sufficient to reach this level. We also reach above 35 degrees with 80% relative humidity.

Analyze the heat we spend.
Various studies have tried to better understand what our limit is. For example, one study between 2013 and 2016 looked at body temperature and other variables of up to 300 wildland firefighters in the United States.

In addition to their work equipment, the participants worked with a device that recorded their skin temperature, heart rate, exhaled carbon dioxide… The study found that physical work played a larger role than expected in firefighters, and vice versa. was correct for the outside temperature.

Another analysis, conducted in a controlled environment, looked at how temperatures and exertion affected participants’ thermal stress, estimating that this time became dangerous at temperatures much lower than the heat indexes of about 44 to 49. -38 degrees at 50% relative humidity.

It’s a global risk.
We got the heatwave news very early this year. In May, India was hit hardest by the high temperatures, but it won’t be long before the first of many heatwaves we’ve had this year reach Spain.

Although the winter months leave a higher death rate in Europe, we have seen several heat waves in recent years that have resulted in tens of thousands of deaths. An example of this was the heatwaves that killed more than 20,000 people in Europe in 2003; or 2010 in Russia with an extreme death rate of 11,000 people.

Ways to avoid the worst heat.
For now, one of the most striking suggestions this summer has been to name the heatwaves. Seville was a pioneer in this regard, but the idea did not come from the municipal authorities, it had already come a long way.

Some experts believe this measure could help raise public awareness of the dangers of heat waves, but recommendations are often based on individual behavior, such as avoiding midday exercise and direct sunlight, wearing appropriate clothing, and drinking plenty of water.

The need to live with the heat is not new in Spain, but this extremely hot and dry summer serves to give us an idea of ​​what the future might hold. There is much more to learn if we are to avoid the worst consequences of rising temperatures and drought that we may experience in the coming years.

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